2i4 The American Geologist. 
October, 1903 
uata were found. These occur generally in the Madison beds. 
That this form reappears here after being absent in the White- 
water, where its place is taken by the Hebertella occidentalis 
(Hall), is an interesting fact in the migration of faunas. A 
well marked form of Platystrophia was found both in the 
western localities and very abundantly at the Dutch creek lo- 
cality. A large number of Bryozoa were collected, which, judg- 
ing from cursory examination, are all new with the exception 
of the Lcptotrypa? stidhami Ulrich. 
III. Xote on the genus Strophomena and its type. 
A very lucid history of this genus is given in Hall and 
Clarke's classic work on the Brachiopoda (Natural History of 
New York, Paleontology, Vol. VIII, Part I, 1892, pp. 245- 
252). The essentials of the early history are as follows: 
In 1820 Rafinesque (Annales generates des Sciences phy- 
siques de Bruxelles, V, p. 232) used the term Strophomenes, 
without definition, in a list of new genera. 
In 1824 Def ranee (Tableau des Corps Organises Fossiles, 
pp. 5 and no) cited twice, without definition, the term Stroph- 
omene, once for shells from Dudley, England, and again in a 
list as containing three fossil species, without giving its author 
or naming any species. 
In 1825 de Blainville (Manuel de Malacologie et Conchy- 
liologie, p. 513, pi. liii, 2, 2a) gave a brief diagnosis of the 
genus.* altered the form to Strophomena, cited for an example 
the Sirophomcna rugose. Rafinesque, stated that the genus con- 
tained only fossil species, to the number of three, according to 
Defrance, and figured the dorsal and ventral aspects of a speci- 
men of the species cited. 
In 1827 (Dictionnaire des Sciences Naturelles, tome LI, p. 
151 ) the description, with slight verbal changes, was repeated. 
* "Strophomene. Strophomena. Animal tout-a-fait inconnu. Coquille 
r6guli&re sym£trique. §quilat§rale. subequivalve ; une valve plate et l'autre 
un peu excavee : articulation droite. transverse, offrant a. droite et ft gauche 
d'une subeehanerure mediane. un bourrelet peu considerable, crgnele ou den- 
tel6 transversalement : aucun indice de support." — de P.lainville. Man. Malac. 
p. 513. [Strophomena. Animal altogether unknown. Shell regular, symmet- 
rical, equilateral, subequivalve ; one valve flat, the other a little hollowed : 
hinge transverse, straight, presenting to the right and left of a median notch 
(delthvrium?K a slight swelling (deltidium?). transversely crenate or den- 
tate: ho indication of support (brachial supports'.'). There is nothing about 
Strophomena planumbona to which such an expression as "transversely cre- 
nate or dentate" can apply. 
